diff options
Diffstat (limited to 'db.go')
| -rw-r--r-- | db.go | 33 |
1 files changed, 18 insertions, 15 deletions
@@ -140,14 +140,8 @@ func Open(path string, mode os.FileMode, options *Options) (*DB, error) { db.MaxBatchSize = DefaultMaxBatchSize db.MaxBatchDelay = DefaultMaxBatchDelay - // Get file stats. - s, err := os.Stat(path) flag := os.O_RDWR - if err != nil && !os.IsNotExist(err) { - return nil, err - } else if err == nil && (s.Mode().Perm()&0222) == 0 { - // remove www from mode as well. - mode ^= (mode & 0222) + if options.ReadOnly { flag = os.O_RDONLY db.readOnly = true // Ignore truncations. @@ -156,21 +150,26 @@ func Open(path string, mode os.FileMode, options *Options) (*DB, error) { // Open data file and separate sync handler for metadata writes. db.path = path + var err error if db.file, err = os.OpenFile(db.path, flag|os.O_CREATE, mode); err != nil { _ = db.close() return nil, err } - // No need to lock read-only file. if !db.readOnly { db.ops.Truncate = db.file.Truncate - // Lock file so that other processes using Bolt cannot use the database - // at the same time. This would cause corruption since the two processes - // would write meta pages and free pages separately. - if err := flock(db.file, options.Timeout); err != nil { - _ = db.close() - return nil, err - } + } + + // Lock file so that other processes using Bolt in read-write mode cannot + // use the database at the same time. This would cause corruption since + // the two processes would write meta pages and free pages separately. + // The database file is locked exclusively (only one process can grab the lock) + // if !options.ReadOnly. + // The database file is locked using the shared lock (more than one process may + // hold a lock at the same time) otherwise (options.ReadOnly is set). + if err := flock(db.file, !db.readOnly, options.Timeout); err != nil { + _ = db.close() + return nil, err } // Default values for test hooks @@ -660,6 +659,10 @@ type Options struct { // Sets the DB.NoGrowSync flag before memory mapping the file. NoGrowSync bool + + // Open database in read-only mode. Uses flock(..., LOCK_SH |LOCK_NB) to + // grab a shared lock (UNIX). + ReadOnly bool } // DefaultOptions represent the options used if nil options are passed into Open(). |